1. Field of the Invention
The present invention relates to an apparatus and method for cleaning the interior of tubular bodies such as heat exchanger tubes and, more particularly, to an apparatus and method for cleaning finned (air cooled) heat exchanger tubes.
2. Description of the Prior Art
Air-cooled heat exchangers are used in many applications in the chemical and refining industry and are particularly used in areas of water scarcity. These air-cooled heat exchangers are comprised of externally finned tubes generally disposed horizontally between spaced headers that define manifold chambers whereby a fluid to be cooled can be introduced into one header, pass through the finned tubes to be cooled, and exit through the opposite header. Although the finned tubes are generally cooled by means of fans to enhance their efficiency, finned heat exchangers are generally mounted at elevated locations to take advantage of greater air movement and air that is generally cooler.
As do all heat exchangers, air-cooled, finned exchangers require periodic cleaning of the tubes to remove scale and other deposits that build up on the interior of the tubes and reduce the heat exchange efficiency of the tubes. To date, this has been a time-consuming and often dangerous operation. For one, as noted above, the finned heat exchangers are generally mounted at elevated locations and sometimes require temporary scaffolding to be built so that the tubes can be accessed for cleaning. The prior art cleaning process is labor-intensive and time-consuming. Finned exchangers are generally constructed such that the finned tubes cooperate with the headers to form tube openings, thereby providing open communication between the manifold chambers formed by the headers and the interior of the tubes. In order to access the tubes for cleaning, removable, threaded plugs are received in bores in the header, such bores being in register with the tube openings. Thus, in a typical prior art cleaning method, a removable plug would be removed from the bore on one header and a corresponding plug removed on the opposite header such that a cleaning wand could be inserted through one of the headers into the tube and run up and down the length of the tube to clean the scale, deposits, etc., from the interior surface of the tube. With the plug removed from the opposite header, the cleaning medium and the dislodged scale and other debris can be removed from the tube being cleaned and collected in a suitable fashion. The tubes are typically cleaned with a pressurized air/solids cleaning medium, and it is important that none of the debris and/or solid cleaning medium be deposited in either of the headers lest this cause plugging or contamination when the exchanger is put back into operation.
Accordingly, in the past, the threaded plug would be removed, bored out, and fitted with a nozzle so that the plug/nozzle assembly could be screwed back into the bore until the nozzle effected a metal-to-metal seal with the tube opening. The source of abrasive would then be attached to the plug containing the nozzle to introduce the cleaning medium into the tube being cleaned. On the opposite end of the tube being cleaned, a spanner tube would be attached to a similarly bored-out plug so that the exiting cleaning medium and/or debris could be expelled from the tube without being deposited in the opposite header.
It will readily be apparent that such an operation is extremely time-consuming and, because of the fact that workers conducting the cleaning may be on temporary scaffolding at considerable height, also quite dangerous.
It would therefore be desirable to have an apparatus for cleaning heat exchanger tubes that can be quickly and easily mounted to the exchanger and will minimize the chances of any solid cleaning medium or debris being deposited in the headers of the exchanger. It would also be desirable to collect and contain the debris and cleaning medium in order to prevent environmental contamination and aid in packaging for disposal.